This invention relates generally to cable conduits and in particular to cable core conduits adapted primarily for use in motion transmitting systems.
There are various forms of motion transmitting systems, and they may be utilized in various applications.
Generally there are two broad categories of cable type motion transmission systems. One form of system might be called a "push-pull" remote control system. That is, the cable core is both pushed and pulled to effect remote control of some servient mechanism, apparatus or device. In the pull mode the tension load is placed on the cable core and very little load is transmitted to the wall of the associated conduit. In the push mode the cable core is placed under a compressive load and a substantial lateral load is transmitted to the wall of the associated conduit. It can be seen therefore that the side walls of the cable conduit are subjected to intermittent loading depending upon the mode of operation.
Another basic form of cable type motion transmission system may be described as a "pull-pull" remote control system. The major difference between this system and the above referred to push-pull system is that in a pull-pull system the cable core is always under tension. That is, the cables are always in a pull mode to effect remote control of a servient mechanism, apparatus or device.
In both of the above forms of systems it is important that cable conduits provide the necessary support and bearing support for the cable core under many varying conditions.
The prior art is replete with many forms of conduits for cable cores for push-pull and pull-pull motion transmission systems. The prior art may be described as highly complex, difficult to manufacture and possessing poor performance characteristics.
A typical example of such prior art is U.S. Pat. No. 2,218,903 to O. J. Braty in which is disclosed a multiple Bowden Wire structure. The Braty structure is provided with a multiplicity of helically wound casings that provide the cable conduits for the various Bowden wires. The Braty Bowden wire conduit structure is highly complex and therefore difficult to manufacture. Additonally the Braty Bowden wire conduit fails to provide a suitable bearing surface for the movable wire dispersed therein. Any small imperfection on the inner surface of the conduit will cause a substantial "drag" on the wire as it moves over the imperfection resulting ultimately in a complete failure of the transmission system. The following prior art patents contain similar deficiencies in that they are complex, expensive to manufacture, are subject to premature wear and failure and provide a poor bearing surface for the slidable core or cable:
U.S. Pat. No. 2,186,181 to Steinlein; U.S. Pat. No. 2,774,382 to Bentley; U.S. Pat. No. 2,787,917 to Schroeder; U.S. Pat. No. 2,931,245 to Jacobson; U.S. Pat. No. 3,438,280 to McCabe; U.S. Pat. No. 3,439,555 to Rech; and U.S. Pat. No. 3,618,420 to Horwitt, et. al.